Loading coil encapsulation



O United States Patent [111 3,54

[72] Inventor Louis Alice FOREIGN PATENTS "klwrymmh Carolin" 995,582 6/1965 Great Britain 114/1 l0(.44) g 2g g fii OTHER REFERENCES u la 8,1970 Machine Design Sept. 17, 1964 p. 94 Penton Publishing [73] Assignee Superior Continental Cleveland Hickory, North Carolina Primary Exam iner Lewis H. Myers in corporation 0' D l i" Assistant Exam inerD. A.'Tone Attorney-Roy B. Moffitt [54] LOADING COIL ENCAPSULATION 23 cmwtnnwinl ABSTRACT: The instant invention discloses the concept of [52] U.S.Cl. 174/52, l i a mass f essentially nongeiatinous, greaseiike 174/55 polyethylene in intimate physical contact with telecommunilllt- Cl. cation loading coils, said loading coils being connected to [50] Field 0' Search 174/525, electrical conductors contained in a cable sheath, Enclosing 52.6, 70.l, 110.44, 65,76, 77; 336/96; 264/272 the grease, coils, and a portion of said conductors is a first container, which is completely enveloped by a second con- [56] References cued tainer composed of a shrunken plastic material possessing an UNITED STATES'PATENTS elastic memory. The grease encapsulating the load coils fills 3,093,448 6/1963 Kirkpatrick et al l74/Shrink the first container and extends for a predetermined length into 3,0l3,l04 12/1961 Young l74/52(.6) that volume created by the sheath of the cable not otherwise 3,439,231 4/1969 Booe l74/5?(.6) occupied by the insulated electrical conductors.

4 yethylene grease PATENTEUBEC-8I970 3.546361 SHEET 1 OF 2 Prior Arf LOUIS ANCE INVENTOR.

ATTORNEY 4 Polyethylene grease PATENTED DEB-8 I970 SHEET 2 OF 2 INVENTOR LOUIS ANCE K K m A TORNFY tainers therefor.

Such assemblies as disclosed herein are normally used in low-voltage level applications such as in connection with voice transmission lines (telephone lines). Because these assemblies are commonly used in a pressurized system, it is therefore imperative to control not only the' electrical but also the mechanical properties associated with these assemblies. Consequently, the design and encapsulation of these assemblies require the upmost consideration so that virtually no change occurs in the coil operating parameters due the presence of water or water vapor inside or outside of a container.

In the main, it is the primary purpose and one of the fundamental objects of the instant invention to provide anand that is adapted to be placed underneath the soil and in association with a pressurized telecommunication network, whereby two simultaneous goals are achieved employing the construction of these assemblies. The goals that are achieved by the disclosed assembly are: (l the exclusion of water or water vapor from the load coils themselves, and (2) a load coil assembly the construction of which in association with a pressurized system is inherently one that does not leak air pressure, when such air pressure is ,in the neighborhood of pounds per square inch gauge and is applied via a cable sheath to the encapsulated coils themselves.

Another object of the instant inventionis to provide a shell structure which when filled with an encapsulate, is capable of withstanding momentary high voltage pulses which may occur at times, for example, over the above mentioned transmission lines or from an outside source.

Furthermore, a further object of the instant invention is to provide an assembly comprising a load coil which when hit by lightening, the inherent heat-sink capabilities of the assembly is such that damage due to lightening and other extraneous currents is essentially nonexistent. Y 1

Other objects, advantages and features of the present inven tion will become apparent from the following detailed description, one embodiment which is present in conjunction with the drawings, in which: I

FIG. 1 shows a fragmentary view of the outer surface and overall configuration of a container enclosing a load coil as in the prior art;

FIG. 2 is a sectional diagram of an enclosed prior art load coil container as shown in FIG. 1;

FIG. 3 is a cutaway portion of the load coil assembly according to the instant invention; and

FIG. 4 is a detailed drawing of the juncture connection between a cable and the assembly in which a load coil is disposed.

Turning now to FIG. 1, there is shown in this drawing an incoming cable 5 carrying electrical conductors. The incoming cable, along with its electrical conductors 7 and 8, passes first through a lead sleeve 16 and into a metal container shown as item 9. This container 9 as well as lead sleeve 16, according to the prior art, was wrapped with a tape as shown by element 14.

The tape usually was on a bias and overlapped each preceeding revolution of tape and was done entirely by hand. Obviously this was a most time consuming and uneconomical process.

Also, according to the prior art, load coils 10 were connected to the electrical conductors 7 and 8 and were then dipped in biwax. This biwax was used solely to mechanically position or set the electrical conductors and to keep them from moving out of position-after being balanced impedancewisewhile the load coils were being assembled into the container 9. That portion of the metal container 9 not otherwise occupied by the electrical conductors, cable sheath, and load coils, was filled with particulatematter shown as 15. This particulate matter was a desiccant for example, calcium chloride.

Assemblies such as that shown in FIGS. 1 and 2-which were in the main that used by the prior art-when employed with a pressurized telecommunications system had its obvious disadvantages. The cable sheath 5 was used to contain a positive pressure, for example, 10 psi. gauge, this pressure being obviously applied to the inside of the container 9. Any pinholes in the cable sheath 5 or any inadvertent or even intentional damage to the container 9 and its outside cover of tape 14 would obviously create leaks in such a pressurized system. Inasmuch as pressurized systems are commonly used for the purpose of keeping moisture out of the telecommunications system and are usually disposed beneath a soil surface, any leaks that would preventthe maintenance of a positive pressure on the inside of the system invited moisture in the form of liquid or vapor to invade the electrical system. Obviously any moisture on the inside of the electrical system, especially in the area of the load coils, created havoc with the telecommunication system as a whole because the change of electrical properties created by the water.

These deficiencies gave rise to the instant invention. The instant invention, which is shown in FIG. 3 is one that is primarily designed but not necessarily limited to be used below the surface of the soil as the assemblies as shown in FIGS. 1 and 2 were also used. In general, the problem solved by the assembly as shown in FIG. 3 is the exclusion of water and/or water vapor from the electrical system (telecommunication system) and .also concominantly with such exclusion, there is presented a system that will maintain the pressure applied to the underground system even though there may be inadvertent or deliberate damage to the container 9 per se that contains the load coils 10 or to the cable sheath such as item 5. Basically these two goals, i.e., the exclusion of water and the ability to maintain a positive pressure, is achieved by a threecomponent assembly.

The first component is that of the container itself that actually contains the load-coil itself. This container is usually a metallic container as shown by item 9 in FIG. 3. Such a metallic container has disposed on its outer surface a three-part plastic covering. This three-part plastic covering is shown by elements 11, 12 and 13. Each one of these elements is a piece of plastic that has an elastic memory. Upon placing this plastic in its position as shown in FIG. 3, and the composite thus made is exposed to heat and the elastic memory of the plastic causes the plastic to shrink and conform to the configuration of the metal container as shown. This heat-shrinkable elastic memory method is well-known; however, for the sake of completeness, to achieve suchresults a thermoplastic material is biaxially oriented by mechanical or other means to create an elastic memory (molecular orientation) in the plastic material. The biaxially orientation can be achieved by pneumatic blowing, or as stated previously, by mechanical stretching. Upon heating the thus stretched thermoplastic material, the elastic memory of the plastic then causes the plastic to shrink into the configuration about which the previously shrunk plastic material is draped.

The second component of the assembly shown in FIG. 3 is that of the load coil itself, item 10, shown in connection with electrical conductors 8, which have an insulation shown at 7. This load coil 10 is completely encapsulated, that is, it is in intimate contact with and surrounded by a polyolifinic greaselike material shown at 4. Both the thermoplastic material used for outer coverings 11, 12 and 13 and the material (thermoplastic) used for the encapsulation 4, are termed as polyethylenes. However, the polyethylene used for the outer covering ll, 12 and 13 is to be sharply distinguished from that polyethylene greaselike material used to fill the cavity created by the container 9 and shown as element 4 in FIG. 3. This greaselike material 4, when subjected to extremes of cold temperatures, will freeze to the point where it may act like a true solid. However, upon returning to more moderate temperatures, this polyethylene greaselike amorphous nongelatinous material will tend to act like an ordinary grease at room temperature. Unfortunately, the term grease is not a term subject to a high precision definition or detailed description like a sol or a gel.

Even when the polyethylene greaselike material has been frozen to a solid like material, it does not tend or have an inservice propensity to remain in such a solid state when more moderate temperatures are reached. However, asphalticlike compounds, when used for the same purpose as polyethylene grease material, tend to permanently harden in service. As a consequence of this hardening, the asphalticlike material flakes and these flakes tend to act like a particulate material rather than a greaselike material when moderate temperatures are again encountered. Dow Corning Corporation, underneath the designation of QX-42 l 3.3, sells this polyethylene grease and has tested it using similar apparatus and method as described in ASTM Dl238-65T incorporated herein by reference. This ASTM designation test method was modified to the extent that a temperature of 100 C. was used on the barrel of the extruder rather than a 125C. temperature. Using the modified process, a melt index of 10-20 was measured with an orifice dimension of 0.020 inches.

Set forth below is a table of physical properties of the polyethylene grease:

Prior investigators have approached the corrosion problem of buried apparatus (assemblies) of the nature such as that disclosed by the instant invention in several different ways. One of the approaches is to encapsulate electronic components with various plastic materials, such as epoxy resins and the like. A good example of such an encapsulation would be that shown in U.S. Pat. No. 3,210,701. l-lowever,it has been observed as result of changes in temperature, i.e., freezing and thawing, that the epoxy tends to shrink away and crack along the innerface between the epoxy resin and any other plastic material that forms an outer casing. it is these cracks, micro scopic or macroscopic in nature, that allow water and/or water vapor to penetrate and reach any electronic component supposedly protected by the epoxy. in the instant invention,

contrary to that approach used by prior investigators, a fiowat ble greaselike material, which is formable and compatible with other polyethylene materials, is used as the encapsulating material. in contradistinction to epoxy resins, the greaselike material does not set even though extremes of temperature (hot or cold) are reached. When such extreme temperatures are moderated down to more normal, e.g. room temperatures, the polyethylene greaselike amorphous nongelatineous material returns to its normal t'iowable state. This greaselike material is made up of polyethylene molecules, has as anv average molecular weight below about 10,000 and a density at 25 C. of about 0.851 grams per milliliter.

Not only does the polyethylene greaselike material completely fill the container 9, but it also fills that interstitial space created by the cable sheath not otherwise occupied by the insulated electrical conductors 7 and 8. Therefore, the grease not only fills container 9 but extends up between the insulated electrical conductors 7 and 8 filling up a major part of sheath 5 to a predetermined length. Note FIG. 4, which shows the polyethylene grease as item 4 extending up into the cable sheath 5 so as to form a covering that protects the insulated conductors 7 and 8 per so as well as the load coil 10 on the inside of the metal container 9.

The third component of the instant invention is that which is shown in FIG. 4. Here, in this drawing, there is shown the con-' ventional cable with its outer sheath 5 and the inner metal tape or jacket 17 and a innermost plastic sheath shown at 6. Both sheaths 5 and 6 are customarily made from a high density and/or low density polyethylene extruded in the conventional manner. Metal sheath 17 can be either copper, aluminum, stainless steel, zinc-coated steel or other various forms of metal in sheet form that is folded during manufacture around the cable core, the core being made up of a plurality of electrical conductors shown at 7 and 8. The metal container, which contains the load coils 10 per se, is shown at 9 and one of the outer coverings 13, which was also shown in H0. 3, is shown associated with that portion (top) of the assembly in which the cable enters the area where the load coil is disposed. This covering, as mentioned previously, is a heat shrunk thermoplastic material. Also contemplated by the instant invention is the embodiment where this covering material could be, if desired, a crosslinked material such as thermoplastic materials (polyethylene or polypropylene) irradiated by suitable apparatus to achieve the crosslinking.

A first sleeve, shown as item 1 in FIG. 4, is attached to container 9. This sleeve is a zinc-coated steel cylindrical neck and is mechanically secured to a second sleeve 2 which is made of lead. This mechanical attachment is by the well-known process of fswetting" one cylindrical metal piece onto another cylindrical metal piece. Such a process involves frictionally engaging sleeve 1 into sleeve 2 and then soldering the thus assembled sleeves together. Obviously, the second sleeve 2 is secured to container 9 and forms an airtight seal therewith. This can be done either by welding or by other wellknown means.

Also shown in FIG. 4 is a dam (a block) or a plug which is denoted by item 3. This block or plug is made out of epoxy and one portion of saidplug adheres to a lead metal sleeve 2 of the container assembly, and another portion of said plug adheres to the metal jacket 17 of the cable. Obviously, the epoxy plug also is in contact with the innermost surface of the outermost plastic sheath 5 as well as the outermost surface of the inner plastic sheath denoted by element 6. As stated before, however, when such an assembly is exposed to alternating freezing and thawing, there are micro and macroscopic cracks associated with and develop along the epoxy and polyethylene innerface. Such cracks could then appear along the innerface between plug 3 and sheaths 5 and 6. On the other hand, a tenacious airtight bond is developed between the epoxy 3 and the metal members 2 and 17.

Viewing FIGS. 3 and 4 one can grasp the method by which the encapsulated load coils are assembled. The first step is to position and assemble the apparatus as shown in FIG. 4, absent any polyethylene grease denoted by element 4. That is to say, an assembly is positioned in the upside down position as shown in FIG. 4 with the sheath 5 bent approximately in the configuration as shown. In this position, a epoxy resin is poured into the cable sheath opening out of which protrude theelectrical conductors 7 and 8. This pouring is continued until the epoxy resin 3 reaches the level or approximate level as that shown in FIG. 4 by element 3. Thus, it can be seen that the epoxy covers all but a small portion of the innermost plastic sheath 6. After the epoxy has harden the composite thus assembled, which is absent the polyethylene grease and the outermost plastic coverings ll, 12 and 13 as well as the metal bottom portion 18 of the metal container 9,'heated polyethylene grease 4 is then poured in through the open bottom and allowed by gravity flow alone to fill up the interstitial spaces between the electrical conductors 7 and 8 inside the cable sheath 5 and 6. The polyethylene greaselike material, when heated, is of such a fluidity that it will easily occupy such interstitial space urged on only by gravity flow. The cable sheath 5, as shown in the bent configuration or the U" configuration and the interstitial space inside the plastic jackets 5 and 6 are such to cause some fn'ction or resistence to fluid flow. it is this friction to fluid fiow that allows the balance of the container 9 to be filled with the polyethylene grease 4 then grease. After this container 9 is filled with the polyethylene grease 4 then the bottom most portion 18 of the metal container 9 is attached (soldered or welded) to the-balance of the metal container 9. The plastic coverings -ll 12 andl3- are then placed intheir proper positionqand heat shrunk to their flowable polyethylene grease 4 into-such ruptures and automatically'same' thereby avoidin'gany kind of leaks from the system as a whole or in this particular assemblyinparticular,

recovery asset. Hence,-it is. desired to recover as many as possible so they may be reused. If a coil were to be removed fromitscase, i.e., container'9, as shown in FIG.- 3, the grease material 14 obviously still wouldremain on the coil 10. If this greasematerial were a'silicone grease, then its removal from the coils per so would present a considerable problem. In-

Air pressure, inthis-instance, must, traverse all through the polyethylene grease disposed in the cable sheath itself before escape is-possible. Consequently,thelpolyethylene greaselike material acts as 'an added barrierair must oyercome before a leak is developed. inservice' and fol-practical purposes there just' are not any-leaks in this system because. of the unique constructionshown herein. 1

During the development of the instant inventiomthewell a known silicone greases were evaluated. incomparison' to. the

polyethylene greaselikematerial. Thisinve'stigation revealed that silicone greases were not desired. One of the many reasons mitigatingagainst silicone grease wasthe fact that silt icone grease tends to be toxic to human beings. Thus, itsuse is asmuch assilicone grease is not readily soluble in any kind of known solvents, aboutthe only other way one could remove the silicone grease from the coils would be by the means of heating the coil and its grease'to the melting point of the grease. Consequently the coil and greasewouldhave to be heated to an excess of 300 F. Such an application of heat is not onlyexpensive but the'heat is detrimental to the coil per se because'thewindings are distorted and suffer from deterioration fromthe applied heat. Hence any recovery of any coils by means of stripping silicone grease from the "coils ias'such, is .somewhat impractical. On the other hand, when the polyethylene greaselike material is employed,'the greaselike material can be stripped from'the coils in' a manner that the =coils'are not at all harmed. Thus, the 'coils can be recovered and reuse d.'A coil encased in polyethylene'greaselike material can be'immersed in any kind "of commercial solvent, for example, benzol, ethynol, trichlorethylene, kerosene, gasoline, carbontetrachloride and the like. Such solvents strip the polyethylene grease from the coil-almost immediately. Alternately, the coil encapsulated and covered with polyethylene greaselike material can be heated in a-heating means-to l300r 140 FJAt this temperature, all of the polyethylene'greaselike material will almost instantly flow off ofthe coils-andrender the coils clean and suitable for reuse,

an obviousliability during any manufacturing processwhere human'beings are involved. Furthermoreythesilicone grease has as a cost factor that is prohibitive. At thefpresent, the sil: icone grease has a cost'betweeh'fi and 5' dollars, per pound whereas the polyethylene" greaselike material .costs in the neighborhood of 201030 cents per-pound. he advantages of using polyethylene g'reaseis therefore quite obvious from this,

standpoint alone. Additionally, the silicone greasehasa melt ing point in the excess, of 300 F. whereas onthe otherhand polyethylene greaselike material has 'a' melting point in the.

t such lowtemperatures being too low to harm the coils per se,

"l he polyethylene greaselike materiahsuch as used by the instant invention'yhas another advantage over that of other materials in'that most sheath materials of telecommunication cables as-that shownby elements Sand 6 inF lG 4 are themneighborhood of 135 F, The. difference in melting: points is quite significant from two standpoints. First, the spaces in the.

cablesheaths 5 and 6 not otherwise occupied bythe' electrical v conductors 7 and 8, are essentially rather. smalLjwhenthere-" are many such small interstitialspaces; there exists when fluid",

flowstherethrough very high frictional forces that'are not con selves made of' polyethylene. Because both the greaselike material and the nongreaselike but solid materials Sand 6 are polyethylene, the two' materials are chemically compatible, Not only are they chemically compatible and one not deleterious to the otherasfa r asthe greaselike material being asource of cracking, corrision and-deterioration to the sheath materials, these two materials'have similar expansion and contractioncoefficients upo'n' changes in temperature. Consequently,

upon the expansionand contraction of the polyethylene sheath likernaterials'5 and 6, the polyethylene greaselike ducive to easy fluid flow. The high viscosity ofthe silicone grease in comparison to the polyethylene greaselikematerial increases the resis'tanceto fluid flow. Thus, .the silicone grease does" not readily flow into these interstitial spacesunder ordinary gravity flow. if one wereto use air pressure toforce the siliconegrease into these smallinterstitial spaces, yoids-are g' created because of the air being blown. byisolatedmasses-of silicone grease. Such a procedurecreates void spacesand-lis,

obviously undesirable. On the other hand,fwhe n onez-uses the polyethylene greaselike material, as disclosed by the instant inventiom'one only-need a gravity, feed .method es pecially when the polyethylene grease is heated to 135 K. (itsfi-j' melting" point). When'gravity, feed is used in combination. v

with heated (l30'F )l polyethylene greaselike material void 2 creation is avoided. Whereas,, when using-. silicone heated to- 300 F this material has a propensity to inherentlycreate'air.

pockets notwithstanding its heatedcondition.

A second advantagein, using. polyethylene greaselike material rather than asilicone grease iis thedifference in their. melting points. In the first place,,lqading'coils (unencapsu lated) are difficult to make, and are ,thereforeexpensive. Con-a sequently, when a'coil is returned tofthe, manufactures-for.

repair or becauseiof a failure-to-live up to a warranty, the Y manufacturer desires to recover as many'parts of the defective coil as'possible.iiice loading coils in the communication field'- are essentially acomposite made upofa plurality of coils,

those coils not otherwise damagedv represent valuable,

material4correspondingly follows. a Contrary to what'the prior art maintains, epoxy resins do not afford anall weather seal against theelements. As stated before,'epoxy resins have a propensity to form microscopic or macroscopic -tra'cts-especiallyat an"'interface between the epoxyand plastic-therefor. This 'is true especially when the container is another plastic material such as polyethylene. On the other f-hand, epoxyresins'do form a tenacious, weathertight, permanent bond to metals. Thus an allweather seal betweenan epoxy and any metal container can be formed.

In the area of technology in which the instantinvention is concerned, i'.e. telecommunications apparatus, the container in which the communications apparatus is enclosed must be .waterrepellent and water resistive as well as waterproof. Any

kind'of moisture, whether-inthe'liquid 'or in thevapor state, is most deleterious to any kind of communications apparatus.

Consequently, the*shielding or the protective coat covering the telecommunication apparatus, especially when buried, -must be-impermeable both to water'and to water' vapor. Micro and/or macro'cracks" developing in any kind of epoxy resinplastic'container preforminterface is so'methingtha't is to be rigoriously avoided. Thus,"the use of epoxy resins to form a seal betweenits'elf and a polyethylene is to be avoided as much as possible-Epoxy i'esins do have however, the property of being able to create a means like that of elementQlithat has considerable mechanical strength. Thisis to be desire d for certain applications. Turning to FIGQ 4 wheretheepoxy resin element 3 is shown and employed, mechanical strength is desired at this particular point. his the reason that an epoxy resin is used in this particular spot. As stated previously, this epoxy bonds itself rather firmly and adhesively to the metal means 2 and to the metal jacket 17 of cables. This bond is not only sufficient to contain the polyethylene greaselike material but also adequate to exclude any water or water vapor from penetrating into the assembled system.

Outer covering elements shown as ll, 12 and 13 are made of a biaxially oriented piece of plastic material. Because of its biaxially orientation, it has an elastic memory. it will be noted that the outer covering of the metal container 9 is made up of three pieces rather than a unitary piece. This three piece operation composite is used because of the particular manufacturing or assembly procedure employed in making up the load coil assembly. Because the polyethylene greaselike material is flowed into the bottom of the container 9, bottom 18 obviously is removed during such an operation. Subsequent to the polyethylene greaselike material being flowed into container 9, element 18 is attached to element 9 to form the composite or unitary container 9. Then, outer coverings ll, 12 and 13 are shrink-fitted onto the encapsulated load coil container 9, this procedure obviously requiring that element 1 1 be shrunk on first and elements 12 and l3shrunk second.

As it has been previously stated, this outer jacket or boot" can be made of irradiated biaxially oriented thermoplastic material. The radiation provides a cross-linking in an otherwise thermoplastic material thereby making the thermoplastic material of elements l1, l2 and 13 more resistive to chemical and mechanical attack. On additional feature of the instant invention is an embodiment that incorporates on the inner surface of boots l1, l2 and 13 a coating of a mastic." This mastic 19 is an asphaltic base, thixotropic adhesive that also contains butyl rubber. ln service it is in contact with the metal container as well as outercoverings ll, 12 and 13. Use of this mastic material is made because when the outer covering, i.e. elements 11, 12 and 13, are either intentionally or unintentionally penetrated by some outside means, the mastic has a propensity to flow and thus tends to heal the injury. I

Turning for a moment to the electricalconductors 7 and 8 as shown in .FIG. 4, these electrical conductors are a metal means or a wire shown as 8 with a covering of some form of thermoplastic or thermosetting material shown as 7. In most every manufacturing process, which'molds the plastic 7 onto the electrical conductor 8, pin holes develop that are either macro or microscopic in nature. The polyethylene grease 4 has an added inservice advantage inasmuch as it is of such a viscosity that it will flow into these pin holes in the insulation 7. inasmuch as most insulated conductors have an insulation 7 made of polyethylene itself, the compatible nature of the polyethylene greaselike material 4 and the insulation 7 is obvious and creates and added protection to the electrical properties of the current carrying wire 8.

While the instant encapsulated load coil is in service, the polyethylene grease has the added property of shielding the load coil from foreign currents. Such foreign currents can be of either high intensity or low intensityjthe low intensity being more likely that of galvanic corrision type and the high intensity being that of lightening or other currents of like magnitude. The greaselike polyethylene material is obviously more re-. sistive to such foreign currents than the prior art desiccant as shown in FlG. 2. This is son because when the foreign currents come in contact with an encapsulated load coil, the desiccant does not create the enormous heat'sink as that developed by the polyethylene greaselike material. Thus, sudden surges of current or heat energy coming in contact with the encapsulated telecommunications load coil will be absorbed by the polyethylene greaselike material, whereas such sources of extraneous energy coming in contact with prior art load coils could not be absorbed in the. desiccant 15. From Table l, the significant water protective nature of the polyethylene greaselike material is immediately ascertainable. The polyethylene grease when exposed for 24 hours'at 100 percent relative humidity absorbs less than 0.01 percent 'water. Obviously this is something to be desired in any kind of telecommunications apparatus, *especially when said apparatus is buried underneath the soil surface.

' The telephone encapsulated load coil as shown in FIG. 3 is sold in commerce essentially in the same configuration as that indicated by the aforementioned FlG. That is to say, a predetermined length of cable indicated by the numeral 5 is sold in association with the encapsulated load coil 10. This length of cable'is merely a matter of arbitrary choice. An installer of telephone load coil assemblies, as that shown in FIG. 3, would splice electrical conductors 7 and 8 to electrical conductors in a preexisting cable trunk. A splice case (not shown) is commonly used at the juncture of sheath 5 and a main trunk cable (not shown). The splicing of the electrical conductors 7 and 8 to like conductors-in the trunk system is inside of the splice case, which is a gas tight container. Thus, an air tight system is created notwithstanding the fact that the load coil assembly is spliced into a preexisting pressurized trunk system Pressurized gas or gasesare then introduced into the interior of the trunk cable and these gases flow along this trunk system and into the load coil sheath 5. The polyethylene grease 4 acts as a blocking means much like thatof a valve. This grease short circuits the flow of air inside cable sheath 5 and does not allow any of the air in the cable sheath to escape from the assembly as shown in FIG. 3. Whether such a system is pressurized or not, water and/or water vapor is excluded from the load coil itself as well as from any of the electrical conductors encased by the polethylene grease 4. I

For the foregoing, it is believed that the invention may be readily understood by those skilled in the art without further description, it being bore in mind that numerous changes may be made in the details disclosed without departing from the spirit of the invention as set forth in the following claims:

lclaim:

i 1. An assembly comprising an electrical circuit electrically connected to a plurality of conductors encased by at least one cable sheath wherein:

a. a container surrounds said circuit and a terminal portion of said electrical conductors; and

b. said cable sheath contains nested therein at least one metallic jacket, said metallic jacket being nested inside of and bonded to a first metallic sleeve means which forms a part of said container.

2. An assembly as defined in claim 1 wherein said cable sheath is nested inside said sleeve means.

3. An assembly as defined in claim 2 wherein an outer cable sheath is in contact with said first sleeve means only at a terminal portion of said first sleeve.

4. An assembly as defined in claim 1 wherein a thermohardenable plastic is disposed between said first metallic sleeve means and said cable metallic jacket and bonded thereto.

5. An assembly as defined in claim 4 wherein said thermohardenable bonding plastic is an epoxy.

6. An assembly as defined in claim 1 wherein said. first metallic sleeve is in frictional engagement with and nested inside of a second metallic'sleeve.

7. An assembly as defined in claim 1 wherein said container and a predetermined volume of the cable sheath, not otherwise occupied by the insulated conductors, are essentially filled with a polyethylene material having a melting point below about 160 F.

8. An assembly as defined in claim 7 wherein said polyethylene material is a greaselike polyethylene.

9. An assembly as set forth in claim 7 wherein said polyethylene material absorbs less than 0.01 percent of its weight of water when exposed to percent relative humidicuit electrically connected to a plurality of electrical conduc-- tors wherein a container surrounds said electrical circuit, a

layer of thixotropic adhesive is disposed on the outside surface of said container, and a plastic material encloses said thixotropic material.

14. An assembly as defined in claim 13 wherein the interior of said container, not otherwise occupied by said electrical means, is essentially filled with a polyethylene material having a melting point below about [60 F.

15. An assembly as defined in claim 14 wherein said polyethylene material is a polyethylene grease.

16. An assembly as defined in claim 14 wherein said plastic enclosing said thixotropic material is a plastic possessing an elastic memory.

17. An assembly as defined in claim 13 wherein the interior of said container, not otherwise occupied by said electrical circuit, is essentially filled with a polyethylene material that absorbs less than 0.01 percent of its weight of water when exposed to 100 percent relative humidity for 24 hours.

18. An encapsulated assembly comprising an electrical cir-.

cuit electrically connected to a plurality of electrical conductors encased by at least one cable sheath, wherein a container surrounds said electrical circuit and a terminal portion of said electrical conductors, saidcontainer and predetermined volume of cable sheath not otherwise occupied by the electrical conductors being essentially filled with a polyethylene material having a melting point below about 160 F., and said container also being essentially enclosed by a plastic material having an elastic memory said plastic material having between it and said container, a thixotropic adhesive material.

19. An encapsulated assembly as set forth in claim 18 wherein said polyethylene material is a polyethylene greaselike material.

20. An encapsulated assembly as set forth in claim 18 wherein said polyethylene material absorbs less than 0.01 percent of its weight of water when exposed to percent relative humidity for 24 hours.

21. An encapsulated assembly as defined in claim 18 wherein said polyethylene material has a dielectricconstant of 2.l5atl--l0OKC,

22. An electrical cable terminus adapted to be connnected to a container comprising at least one insulated electrical conductor surrounded by and nested in a metallic shield, said metallic shield being nested in and surrounded by a cable sheath, and said cable sheath being surroundedby and nested in a tubular metallic member whose sidewall is spaced apart from the outermost surface of said cable sheath, thereby forming an annular space between said tubular member and said cablesheath, and a thermohardenable plastic disposed in said annular space and bonded to both the metallic shield and tubular means.

23. An assembly as defined in claim .22 wherein said thermohardenable bonding material is an epoxy. 

